The fungal cell wall serves as an osmoprotectant, a determinant of fungal cell shape, and more importantly as a defense against attack by immune system cells. Fungal and yeast infections caused by Aspergillus and Candida spp. are common nocosomial infections in immunocompromised patients, including individuals with AIDS, cancer, and who have undergone organ transplantation. The invasiveness of the infection often leads to mortality among these patients. In order to design effective antifungal agents, knowledge of fungal cell wall structure and remodeling processes is imperative. In this subproject, titled Evolving Fungal Cell Surfaces: Characterization by Atomic Force Microscopy, the structure of Penicillium cell walls and wall remodeling processes will be investigated using a promising new instrument, the atomic force microscope (AFM). Penicillium will be used in these investigations as it serves as a good model for Aspergillus and Candida spp., as they are related organisms. ln this subproject, we propose to examine the effect of endogenous glycohydrolases, acid phosphatases, and cell wall biosynthesis inhibitors, on cell wall structure. Our subproject research goals are to: (1) identify the effect of extracellular hydrolases (cellulases, galactofuranosidases, and acid phosphatases) on Penicillium fellutanum cell walls with structural changes in mycelial glycopeptides and polysaccharides; (2) identify the effect of cell wall biosynthesis inhibitors on Penicillium fellutanum cell walls with structural changes in mycelial glycopeptides and polysaccharides; and (3) adapt and establish a procedure for the examination of fungal cell surfaces and structures using atomic force microscopy. In order to support these research goals, we have requested funding for 25% effort for both the principal investigator and the co-investigator, a full-time technician, accompanying summer salaries for faculty, travel, a 6 micron AFM scanner head, a Tektronix printer for image printing, and other project costs. Results from our investigations are expected to yield a minimum of 4 publications, 10 presentations, and one non-SCORE grant in the four year period of support. The activities in this proposal are aimed at developing new AFM techniques for the study of biological and evolving surfaces and will contribute to the knowledge of cell wall structure and remodeling.